The article concerns the exact solution of the two-dimensional problem by the partial areas techniques of determining of the acoustic field around the soundproof screen, which is located at the acoustically hard surface. The sound source is an interminable cylinder of small wave sizes, working at zero mode. There is an analysis of the effect of certain parameters of the screen (height, slope angle), parameters of the sound source (frequency, distance to the screen), and the impact of the relief (slope angle of the half-hard surface to the screen) on the efficiency of noise reduction. For the first time there is a study of the nonmonotonic behavior of the screen field efficiency in the acoustic shadow, which is a significant factor in the development of engineering methods of screen efficiency calculation. The directions of the maximum and minimum noise reduction behind the screen, and the influence of certain parameters on them were determined. The results may be useful for engineers and scientists working in the field of acoustic ecology and noise reduction. The results obtained allow us to estimate the efficiency of already created soundproof screens as well as those that are only being designed